Recently, in signal transmission in an electronic apparatus or between electronic apparatuses, there has been demand for a technique of treating large volumes of data or transmitting large volumes of data at a high speed (for example, on a real time basis). In the past, typically, signal transmission is performed through connection of electric wiring lines. As a technique for implementing high-speed signal transmission, for example, LVDS (Low Voltage Differential Signaling) is known. However, in accordance with further increase in amount of transmission data and further increase in speed of transmission recently, increase in power consumption, increase in effect of signal distortion caused by reflection and the like, increase in unnecessary radiation and the like have become problems. For example, the LVDS reaches a limit where a signal such as a video signal (including an imaging signal), a computer image or the like is transmitted at a high speed (on a real time basis) in an apparatus.
As a countermeasure against the problem of the increase in speed of transmission data, it seems a possible idea to increase the number of wiring lines to decrease the transmission speed per one signal line by parallel transmission of signals. However, the countermeasure just described gives rise to an increase in the number of input and output terminals. As a result, complexity of a printed board or a cable wiring scheme, an increase in the size of a semiconductor chip and so forth are necessary. Further, since a large amount of data is transmitted at a high-speed along a wiring system, a problem of electromagnetic field interference occurs.
All of the problems involved in the LVDS or the technique of increasing the number of wiring lines are caused by transmission of a signal through an electric wiring line. Therefore, as a method for solving a problem caused by transmission of a signal along an electric wiring line, for example, JP-A-2005-204221 and JP-A-2005-223411 propose methods of transmitting a transmission target signal (data main part) by eliminating electric wiring lines, that is, by using a technique of the communication processing.